U.S. patent number 10,052,032 [Application Number 14/784,698] was granted by the patent office on 2018-08-21 for stenosis therapy planning.
This patent grant is currently assigned to KONINKLIJKE PHILIPS N.V.. The grantee listed for this patent is KONINKLIJKE PHILIPS N.V.. Invention is credited to Michael Grass, Dirk Schaefer, Holger Schmitt.
United States Patent |
10,052,032 |
Grass , et al. |
August 21, 2018 |
Stenosis therapy planning
Abstract
The present invention relates to stenosis therapy planning. A
first volumetric data set is received by medical imaging of at
least part of an artery comprising a stenosis. At least one
two-dimensional image data (of the stenosis is received. A first
arterial pressure drop is determined around the stenosis. A second
volumetric data set is generated by registering the at least one
two-dimensional image data with the first volumetric data set. A
third volumetric data set is generated by simulating a geometry
modification of the stenosis in the second volumetric data set and
a second arterial pressure drop is estimated around the stenosis in
the third volumetric data set.
Inventors: |
Grass; Michael (Buchholz in der
Nordheide, DE), Schaefer; Dirk (Hamburg,
DE), Schmitt; Holger (Luetjensee, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
KONINKLIJKE PHILIPS N.V. |
Eindhoven |
N/A |
NL |
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Assignee: |
KONINKLIJKE PHILIPS N.V.
(Eindhoven, NL)
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Family
ID: |
48143477 |
Appl.
No.: |
14/784,698 |
Filed: |
April 16, 2014 |
PCT
Filed: |
April 16, 2014 |
PCT No.: |
PCT/EP2014/057758 |
371(c)(1),(2),(4) Date: |
October 15, 2015 |
PCT
Pub. No.: |
WO2014/170385 |
PCT
Pub. Date: |
October 23, 2014 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160066795 A1 |
Mar 10, 2016 |
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Foreign Application Priority Data
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Apr 18, 2013 [EP] |
|
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13164233 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B
5/026 (20130101); A61B 5/02007 (20130101); A61B
5/0215 (20130101); A61B 5/742 (20130101); A61B
5/6851 (20130101); A61B 8/14 (20130101); A61B
2090/3782 (20160201); A61B 2034/105 (20160201); A61B
2090/364 (20160201); A61B 5/055 (20130101); G16H
50/50 (20180101); A61B 2034/107 (20160201); A61B
6/032 (20130101); A61B 2034/104 (20160201); A61B
6/037 (20130101) |
Current International
Class: |
A61B
6/03 (20060101); A61B 5/026 (20060101); A61B
5/0215 (20060101); A61B 5/02 (20060101); A61B
5/00 (20060101); A61B 8/14 (20060101); A61B
5/055 (20060101); A61B 90/00 (20160101); A61B
34/10 (20160101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102008014792 |
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Jun 2009 |
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DE |
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2004025572 |
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Mar 2004 |
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WO |
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200661814 |
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Jun 2006 |
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WO |
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200661815 |
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Jun 2006 |
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WO |
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201022762 |
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Mar 2010 |
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WO |
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2012011036 |
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Jan 2012 |
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WO |
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2012173697 |
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Dec 2012 |
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WO |
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Other References
DeBruyne, B., et al.; Fractional Flow Reserve-Guided PCI versus
Medical Therapy in Stable Coronary Disease; 2012; The New England
Journal of Medicine; 367(11)991-1001. cited by applicant .
Feuchtner, G. M., et al.; Multislice Computed Tomography for
Detection of Patients with Aortic Valve Stenosis and Quantification
of Severity; 2006; Journal of the American College of Cariology;
47(7)1410-1417. cited by applicant .
Neubauer, A. M., et al.; Clinical Feasibility of a Fully Automated
3D Reconstruction of Rotational Coronary X-Ray Angiograms; 2010;
Circ. Cardiovasc. Interv.; 3:71-79. cited by applicant .
Philips; Interventional X-Ray: Allura 3D-CA; 2004 Koninklijke
Philips Electronics N.V.
www.healthcare.philips.com/main/products/interventional_xray
accessed Aug. 4, 2015. cited by applicant .
Tonino, P. A. L., et al.; Fractional Flow Reserve versus
Angiography for Guiding Percutaneous Coronary Intervention; 2009;
The New England Journal of Medicine; 360:213-224. cited by
applicant.
|
Primary Examiner: Remaly; Mark
Claims
The invention claimed is:
1. A system, comprising: a processor configured to receive a first
volumetric data set of at least part of an artery, said part
comprising a stenosis, wherein the first volumetric data set is
generated by a computed tomography scanner; receive at least one
two-dimensional data of the stenosis; receive first arterial
pressure drop information, said first arterial pressure drop
information being an arterial pressure drop around the stenosis;
register the first volumetric data set with the at least one
two-dimensional data to obtain a second volumetric data set; modify
a geometry of the stenosis in the second volumetric data set which
generates a third volumetric data set; and estimate a second
arterial pressure drop around the geometrically modified stenosis
in the third volumetric data set by modifying the first pressure
drop based on a change in diameter of the artery or by estimating a
proximal and a distal arterial pressure relative to the stenosis
after the geometry modification.
2. The system according to claim 1 wherein, the processor is
configured to use the first arterial pressure drop as a starting
point to estimate the second arterial pressure drop.
3. The system according to claim 1, further comprising: a display
device comprising at least one selected from a group comprising of
a monitor and a printout; and wherein the processor is further
configured to display the first arterial pressure drop and the
second arterial pressure drop on the display device.
4. The system according to claim 1, the processor further
configured to generate at least two third volumetric data sets,
each of the at least two third volumetric data sets being simulated
using a different geometry modification; and to estimate the second
arterial pressure drop for each of the at least two third
volumetric data sets; and wherein the processor is further
configured to display the second arterial pressure drop for each of
the at least two third volumetric data sets on the display
device.
5. The system according to claim 1, wherein the processor is
further configured to calculate a first fractional flow reserve
from the first arterial pressure drop and a second fractional flow
reserve from the second arterial pressure drop; and the processor
is further configured to display the first fractional flow reserve
and the second fractional flow reserve on the display device.
6. The system according to claim 1, wherein the geometry
modification is a reduction of the geometry of the stenosis,
preferably a removal of the stenosis.
7. A method, comprising receiving a first volumetric data set by
medical imaging of at least part of an artery, said part comprising
a stenosis, wherein the first volumetric data set is generated by a
computed tomography scanner; receiving at least one two-dimensional
image data of the stenosis; determining a first arterial pressure
drop around the stenosis as a difference between a determined
arterial pressure proximal to the stenosis and a determined
arterial pressure distal to the stenosis; generating a second
volumetric data set by registering the at least one two-dimensional
image data with the first volumetric data set; simulating a
geometry modification of the stenosis in the second volumetric data
set which generates a third volumetric data set; and estimating a
second arterial pressure drop around the geometrically modified
stenosis in the third volumetric data set by modifying the first
pressure drop based on a change in diameter of the artery or by
estimating a difference between a proximal and a distal arterial
pressure relative to the stenosis after the geometry
modification.
8. The method according to claim 7, wherein the first arterial
pressure drop information was determined from non-invasive imaging
data; or from data received from a catheter comprising a pressure
wire to measure a pressure drop around the stenosis; said measured
pressure drop forming the first pressure drop information.
9. The method according to claim 7, wherein the first arterial
pressure drop is used as a starting point in the estimation of the
second arterial pressure drop.
10. The method according to claim 7, further comprising displaying
the first arterial pressure drop and the second arterial pressure
drop.
11. The method according to claim 7, wherein the at least one
two-dimensional image data comprises at least two two-dimensional
image data which were acquired along different projection
directions with regard to the stenosis.
12. The method according to claim 7, wherein the geometry
modification is a reduction of the stenosis, preferably a removal
of the stenosis.
13. The method according to claim 7, further comprising: generating
at least two third volumetric data sets, each of the at least two
third volumetric data sets being simulated using a different
geometry modification; and simulating the second arterial pressure
drop for each of the at least two third volumetric data sets.
14. The method according to claim 13, further comprising displaying
each second arterial pressure drop for each of the at least two
third volumetric data sets.
15. A non-transitory computer storage medium comprising
instructions which when executed cause one or more processor to
perform the steps of the method according to claim 7.
Description
CROSS-REFERENCE TO PRIOR APPLICATIONS
This application is the U.S. National Phase application under 35
U.S.C. .sctn. 371 of International Application No.
PCT/EP2014/057758, filed on Apr. 16, 2014, which claims the benefit
of European Patent Application No. 13164233.2, filed on Apr. 18,
2013. These applications are hereby incorporated by reference
herein.
FIELD OF THE INVENTION
The present invention generally relates to stenosis therapy
planning, in particular interventional stenosis therapy planning,
such as virtual stenting.
BACKGROUND OF THE INVENTION
Degenerative stenosis is the second most common cardiovascular
disease with an incidence of 2-7% in the Western European and North
American populations aged beyond 65 years, as described in G. M.
Feuchtner, W. Dichtl, et al. "Multislice Computed Tomography for
Detection of Patients With Aortic Valve Stenosis and Quantification
of Severity", Journal of the American College of Cardiology 2006,
47 (7), 1410-1417. In the context of the present invention the term
stenosis represents any abnormal narrowing of an artery. In
interventional cardiology a degree of stenosis may be determined
using fractional flow reserve (FFR) techniques in which a catheter
is introduced into a coronary artery, which is able to measure a
relative difference between pressure behind (distal to) and before
(proximal to) a stenosis in the artery. Alternatively, medical
imaging (such as computed tomography, NMR, PET and the like) may be
used as a non-invasive method to determine a degree of stenosis by
performing FFR calculations based on reconstructed arterial
information. Interventional therapy to treat an arterial stenosis,
such as ballooning or stenting, may be applied (directly) after the
degree of stenosis is determined. Unfortunately it is not always
possible to accurately and/or effectively plan the interventional
therapy, since it is not always possible to determine the effect of
the therapy beforehand. This may result in non-optimal results or
may even require a follow-up interventional procedure, which, in
both cases, is not in a patient's best interest.
To assist therapy planning a procedure known as virtual stenting is
known in which stent placement is simulated based on determined or
modeled artery dimensions and degree of stenosis. U.S. Pat. No.
8,157,742 discloses a procedure in which arterial dimensions and
degree of stenosis are determined and modified using a previously
obtained computed tomography scan and fractional flow reserves of a
stenosed artery and its surroundings.
A drawback of such a procedure is that arterial dimensions and/or
degree of stenosis are modeled with insufficient accuracy due to
imaging errors (artifacts) and/or because certain assumptions made
may be incorrect. Medical imaging of cardiac arteries is
particularly complicated and prone to even more artifacts due to
constant movement of the cardiac area. Further modeling is
necessary to overcome this, for which further assumptions and
corrections need to be made, causing further risks of not
accurately determining the arterial dimensions and degree of
stenosis before or after the virtual stent is placed, and, as a
consequence, a physician may not select an optimal treatment.
The method of the present invention provides, amongst others, a
solution to the previously stated problem.
SUMMARY OF THE INVENTION
Embodiments according to the present invention are directed to a
method for planning an arterial stenosis therapy comprising
receiving a first volumetric data set by medical imaging of at
least part of an artery, said part comprising a stenosis; receiving
at least one two-dimensional image data of the stenosis;
determining a first arterial pressure drop around the stenosis;
generating a second volumetric data set by registering the at least
one two-dimensional image data with the first volumetric data set;
generating a third volumetric data set by simulating a geometry
modification of the stenosis in the second volumetric data set; and
estimating a second arterial pressure drop around the stenosis in
the third volumetric data set. In this method three-dimensional
imaging data obtained by non-invasive medical imaging of a stenosed
artery is combined with a set of two-dimensional images of the same
artery, resulting in a data set which represents the actual
stenosed artery closer than a data set based on either of the
individual data sets. A simulation of modification of a stenosis
geometry is more reliable, since the combined data set provides a
much more realistic starting point, especially when combined with
determined arterial pressure data.
Another embodiment of the present invention is directed towards
using the first arterial pressure drop as a starting point in the
estimation of the second arterial pressure drop. This allows for an
even further improved simulation of the second arterial pressure
drop, since it is based on actual arterial pressure data.
Another embodiment of the present invention is directed towards the
method further comprising displaying the first arterial pressure
drop and the second arterial pressure drop. A user, such as a
physician, may immediately see an effect of the geometry
modification when the actual and estimated arterial pressure are
displayed.
Another embodiment of the present invention is directed towards
that the at least one two-dimensional image data comprises at least
two two-dimensional image data which were acquired along different
projection directions with regard to the stenosis. This allows for
imaging at least partially obscured tissue and for improved
matching the at least two-dimensional image data with the first
volumetric data.
Another embodiment of the present invention is directed towards the
method, wherein the geometry modification is a reduction of the
stenosis, preferably a removal of the stenosis. Reducing or
removing the stenosis corresponds with a desired result of an
arterial stenosis therapy and therefore may be used to predict an
effect and efficiency thereof.
Another embodiment of the present invention is directed towards the
method further comprising generating at least two third volumetric
data sets, each of the at least two third volumetric data sets
being simulated using a different geometry modification; and
simulating the second arterial pressure drop for each of the at
least two third volumetric data sets. By simulating pressure drops
for different geometry modifications, an effect and efficiency may
be simulated for different potential arterial stenosis therapies. A
physician may then determine which therapy has a best potential of
being successful or most effective.
Another embodiment of the present invention is directed towards the
method further comprising displaying each second arterial pressure
drop for each of the at least two third volumetric data sets.
Displaying all the estimated arterial pressure drops allows a user,
such as a physician, to conveniently see the effect of each
geometry simulation, which will assist him in select the optimal
stenosis therapy.
Another embodiment of the present invention is directed towards the
method further comprising a first fractional flow reserve that is
calculated from the first arterial pressure drop and a second
fractional flow reserve that is calculated from the second arterial
pressure drop; and wherein the first fractional flow reserve and
the second fractional flow reserve are displayed. A fractional flow
reserve is an often used property of arterial flow properties to
determine a degree of stenosis. Providing a physician with this
information will further assist him to select the optimal arterial
stenosis therapy.
Another embodiment of the present invention is directed towards the
method, wherein the medical imaging is performed with a medical
imaging technique selected from a group comprising computed
tomography, position emission tomography, single positron emission
computed tomography, magnetic resonance imaging, 3D X-ray imaging,
ultrasound imaging, or combinations thereof. These are non-invasive
imaging techniques which are available at most hospitals or
diagnostic centers.
Another embodiment of the present invention is directed towards the
method wherein the modification of the geometry of the stenosis is
a narrowing (worsening) of the stenosis. A simulated enlargement
may be used to predict how a stenosis might affect flow properties
in the artery if the stenosis would remain untreated and
worsen.
Still further aspects of the present invention are directed towards
a system for planning an arterial stenosis therapy, a computer
program product for planning an arterial stenosis therapy and a
method for selecting an arterial stenosis therapy.
Still further aspects and embodiments of the present invention will
be appreciated by those of ordinary skill in the art upon reading
and understanding the following detailed description. Numerous
additional advantages and benefits will become apparent to those of
ordinary skill in the art upon reading the following detailed
description of preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is illustrated by drawings of which
FIG. 1 shows an example of acquisition of volumetric coronary
artery stenosis data by medical imaging, in this example with a CT
scanner.
FIG. 2a,b shows two examples of acquisition of two-dimensional data
of a stenosis by medical imaging, in these examples with
respectively a two-dimensional X-ray imager and in-artery
imaging.
FIG. 3 shows an example of pressure measurement around a
stenosis.
FIG. 4 shows various geometry modifications of a stenosis therapy
according to embodiments of the present invention.
FIG. 5 shows a method for planning an arterial stenosis therapy of
an embodiment according to the present invention.
FIG. 6 shows an alternative method for planning an arterial
stenosis therapy of an embodiment according to the present
invention.
FIG. 7 shows a further alternative method for planning an arterial
stenosis therapy of an embodiment according to the present
invention.
FIG. 8 shows a method for selecting an arterial stenosis therapy of
an embodiment according to the present invention.
The invention may take form in various components and arrangements
of components, and in various process operations and arrangements
of process operations. The drawings are only for the purpose of
illustrating preferred embodiments and are not to be construed as
limiting the invention. To better visualize certain features may be
omitted or dimensions may be not be according to scale.
DETAILED DESCRIPTION OF EMBODIMENTS
A physician confronted with a patient with a known or suspected
arterial stenosis, in particular a coronary artery stenosis, has
several treatment options to treat the stenosis by reducing or
removing the stenosis, including, but not limited to placing a
stent, a ballooning procedure, bypass or other surgery, prescribing
medication or a diet, advice lifestyle changes or even take a
decision to perform no action at that moment and keep monitoring
the situation over time and defer treatment to a later moment in
time. If the physician has access to a reliable prediction of an
outcome of one or more treatment options, he may better plan and
select a most effective treatment.
In the present invention the patient undergoes at least two imaging
procedures: a (non-invasive) medical imaging procedure to obtain a
volumetric (three-dimensional) data set and a medical imaging
procedure to obtain two-dimensional images along different
projection directions. Furthermore, an arterial pressure drop is
determined around the stenosis, which in the context of the present
invention should be interpreted as a difference between a
determined arterial pressure before (proximal to) and behind
(distal to) the stenosis, wherein both arterial pressures are
preferably determined relatively close to the stenosis.
FIG. 1 shows a schematic depiction of a medical imager 10 to
acquire a volumetric data set, in this embodiment a computed
tomography (CT) scanner, but the medical imaging procedure to
obtain a volumetric data set may be any other technique known by a
person skilled in the art such as, but not limited to position
emission tomography (PET), single positron emission computed
tomography (SPECT), magnetic resonance imaging (MRI), (3D) X-ray
scanning, ultrasound imaging and combinations thereof. A patient is
scanned to obtain a volumetric data set, such as a three
dimensional image 11 of an artery 12, in this example a coronary
artery, comprising a stenosis 13. The volumetric data set may
comprise a full scan of the part of the artery and its surroundings
or the part of the artery 12 may be segmented from the full scan by
segmentation means known to a skilled person in the art. In this
embodiment the volumetric data set consists of a segmented part of
the artery. Arterial dimensions and stenosis geometry and location
may be determined from the volumetric data set.
FIG. 2 shows schematic depictions of medical imagers (20, 20') to
acquire at least one two-dimensional image data (21, 21') that may
be used as alternatives or in combination. A person skilled in the
art would appreciate that in addition to these two examples other
invasive or non-invasive medical imaging techniques suitable to
obtain two-dimensional image data of a stenosed artery may be used
as well. Arterial dimensions and stenosis geometry and location may
also be determined from the at least one two-dimensional image
data. It is preferred that the at least one two-dimensional image
data comprises at least two two-dimensional image data which were
acquired along different projection directions with regard to the
stenosis. This allows for imaging at least partially obscured
tissue and for improved matching the at least two-dimensional image
data with the first volumetric data.
In FIG. 2a a two-dimensional X-ray scanner 20 is used to acquire
two-dimensional image data 21 from different angles of the stenosis
13 in the artery 12. An advantage of two-dimensional X-ray imaging
is its high spatial and temporal resolution and its availability at
most suitable medical treatment centers.
In FIG. 2b in-artery imaging 20' is acquired to obtain
two-dimensional image data 21' of the stenosis 13 in the artery 12.
In this example a catheter 22 equipped with two-dimensional imaging
means 23, for instance ultrasound imaging means or a camera, at its
tip is introduced into the coronary artery 12 and guided towards
the stenosis 13. The imaging means 23 collects image data of the
artery near the stenosis, such as the artery before (proximal to)
the stenosis 13, of the stenosis 13 itself and the artery behind
(distal to) the stenosis 13. It might be necessary that, if
possible, the catheter 22 is introduced from the other side of the
artery as well to be able to achieve this. An advantage of
in-artery imaging is that actual image data of the stenosed artery
is obtained, instead of reconstructed data obtained from
non-invasive imaging that may contain artifacts, imaging errors
and/or reconstruction errors. Furthermore, a patient is not exposed
to possibly damaging irradiation that is inherent with many
non-invasive imaging techniques, such as X-ray imaging. Also,
in-artery imaging may be less sensitive to movement of the cardiac
area, because an in-artery imager moves more or less together with
the artery during cardiac movement. And since arterial stenosis
therapies often already involve catheterization, the patient may
already be prepared for this procedure and the imaging and the
therapy may be performed shortly after each other, in one
embodiment even with a single multifunctional catheter.
FIG. 3 shows an example of measuring arterial pressure around the
stenosis using a pressure wire 31. A catheter 30, which may be a
multi-functional catheter that also comprises imaging and/or
treatment functionality, with pressure wire 31 is introduced into
the stenosed artery 12. Arterial pressure is measured in a proximal
spot 32 before the stenosis 13 and in a distal spot 33 behind the
stenosis 13. Preferably the arterial pressure of the distal spot 33
is measured from the proximal side with the pressure wire extending
through the stenosed area to the distal spot 33. If this is not
possible, for instance because the stenosis fully or nearly fully
blocks the artery 12, the distal spot 33 should be reached from the
other side of the artery if possible. Alternatively arterial
pressure may also be measured from non-invasive imaging data, but
in this case the measurement is in the form of pressure data
modeled from image data. An arterial pressure drop is defined and
determined as a difference between the measured arterial pressure
at the proximal spot (proximal arterial pressure) and the measured
arterial pressure at the distal spot (distal arterial pressure).
Arterial pressure can be very accurately measured using a pressure
wire and provides actual pressure data, instead of modeled pressure
data. In an embodiment of the present invention the arterial
pressure is determined on multiple distal and/or proximal spots
farther away from the stenosis in the artery and/or in connected
arteries of an arterial tree, such that a pressure map may be
obtained throughout the artery and/or the arterial tree to
determine effects of the stenosis in areas that are more remote
from the stenosis.
A fractional flow reserve may be determined using the measured
proximal and distal arterial pressure. The fractional flow reserve
is an often used arterial flow property to determine a degree of
stenosis that is defined as a ratio between the distal arterial
pressure and the proximal arterial pressure. Providing a physician
with this information will further assist him to select an optimal
arterial stenosis therapy.
A processor is configured to receive information comprising the
volumetric data set as a first volumetric data set, the at least
one two-dimensional image data along different projections, the
pressure drop as a first pressure drop, and, optionally, the
fractional flow reserve as a first fractional flow reserve and/or
further image or other relevant data. The processor may receive
some or all information from the medical imagers and, if
applicable, measurement devices in real-time during imaging or
shortly after imaging or measuring. The processor may also receive
some or all of the information from a database on which said some
or all information may have been previously stored from previously
acquired medical imaging procedures and/or measurements.
The processor is further configured to generate a second volumetric
data set by registering the at least one two-dimensional image data
with the first volumetric data set. This allows for an improved
volumetric data set, since artifacts and/or imaging errors or
inclarities in the first volumetric data set may be checked against
other imaging data, and consequently corrected. Imaging data
obtained by in-artery imaging that represents an actual situation
is particularly useful in this respect.
The processor is further configured to generate a third volumetric
data set by simulating a geometry modification of the stenosis in
the second volumetric data set. FIG. 4 shows various examples of
such a geometry modification. In this figure a schematic graphical
depiction is shown of the second volumetric data set 40 comprising
the part of the artery 12 with stenosis 13 and the proximal spot 32
and the distal spot 33 where the arterial pressure was measured.
The geometry of the stenosis may be modified by modeling a partial
or complete reduction of the stenosis (depicted in the figure by an
area with a dashed line representing a section that was removed
from the stenosis) to obtain a third volumetric data set 41, 41',
41''. This simulates an effect of a selected stenosis therapy, such
as placing a stent, a ballooning procedure or another procedure.
The geometry reduction may be tuned to a particular therapy, such
as different sized stents or balloons. It may also serve as
providing a baseline for an effect over time of a possible
treatment by medication to reduce the stenosis.
Alternatively the geometry modification may be a further narrowing
(worsening) of the stenosis to reduce or even close a throughway
through the artery (depicted in the figure by a dashed area that
represent a section that was added to the stenosis) to obtain a
third volumetric data set 42, 42', 42'' or the arterial tree. This
may be used to predict an effect over time in case the stenosis is
not treated, which could provide valuable information to the
physician and the patient about an urgency of the need to treat the
stenosis.
The processor is further configured to estimate a second arterial
pressure drop around the stenosis 13 in the third volumetric data
set 41, 41', 41'', 42, 42', 42''. In the case of a fully removed
stenosis simulation the term `pressure drop around the stenosis`
should be interpreted as the `pressure drop around the former
location of the stenosis`. The second arterial pressure drop may be
estimated by modifying, for instance scaling, the first pressure
drop based on a change in an arterial diameter at the stenosis
location due to the geometry modification. Alternatively, the
second arterial pressure drop may be estimated by estimating a new
proximal and distal arterial pressure in a situation after the
geometry modification. A second fractional flow reserve may be
calculated based on the second arterial pressure drop. Estimation
of the second arterial pressure drop is much more reliable, because
it is based on a more reliable volumetric data set which provides
an improved starting point for the estimation that is much closer
to a real situation than in the case where the second arterial
pressure drop is estimated from just the first volumetric data set
or two-dimensional image data.
In a further embodiment of the present invention the processor may
be configured to generate at least two third volumetric data sets,
wherein each of the at least third volumetric data sets is
simulated using a different geometry modification. For each of the
at least geometry modification a second arterial pressure drop, and
optionally, a second fractional flow reserve, is estimated. This
allows providing information regarding various potential arterial
stenosis therapies that are pre-selected by the physician. The
processor may therefore be configured to receive input from preset
or physician-suggested arterial stenosis therapies.
The processor may be further configured to display the first
arterial pressure drop and the second arterial pressure drop or
drops (and/or the second fractional flow reserve or reserves). This
may be displayed on a display device (which may be a monitor, a
print-out or any other suitable display device) in numerical,
graphical or any other useful form to provide the physician with a
clear and reliable prediction of the effect of one or more arterial
stenosis therapies. Alternatively, the processor may be further
configured to process the first arterial pressure drop and the
second arterial pressure drop or drops (and/or the second
fractional flow reserve or reserves) for further calculation.
FIG. 5 shows a schematic representation of an embodiment of a
method for planning an arterial stenosis therapy according to the
present invention. In step 101 a first volumetric data set of at
least part of an artery comprising a stenosis and in step 102 at
least one two-dimensional image data along different projection
directions of the stenosis is received. In step 103 a first
arterial pressure around the stenosis is determined. In step 104 a
second volumetric data set is generated by registering the at least
one two-dimensional image data with the first volumetric data set.
In step 105 a third volumetric data set is generated by simulating
a geometry modification of the stenosis in the second volumetric
data set. In step 106 a second arterial pressure drop around the
stenosis in the third volumetric data set is estimated. In step 109
the first arterial pressure drop and the second arterial pressure
drop are displayed. Alternatively step 109 may be omitted and
replaced by further processing of the first and second arterial
pressure drops.
FIG. 6 shows a schematic representation of an extension of the
embodiment of FIG. 5. In this case two further third volumetric
data sets are generated in steps 105' and 105'', for which, in
steps 106' and 106'', for each a second arterial pressure is
estimated. It is of course also possible to generate just one or
more than two further third volumetric data sets and to estimate a
second arterial pressure for each. In step 109 the first pressure
drop and each estimated second pressure drop is displayed.
FIG. 7 shows a schematic representation of another extension of the
embodiment of FIGS. 5 and 6. In this case fractional flow reserve
is calculated from the second pressure drop in step 108 and
displayed in step 109. Of course a fractional flow reserve may be
calculated (steps 108', 108'') and displayed for further third
volumetric data sets.
The methods described above and other similar or related
embodiments may be provided as instructions for a computer program
product, which are executed when the computer program product is
run on a computer.
FIG. 8 shows a schematic representation of a method for selecting
an arterial stenosis therapy. A physician may pre-select one or
more arterial stenosis therapies (step 801, 801', 801'') and
perform the method of the embodiment of FIG. 5, 6 or 7 or
variations thereof (step 802, 802', 802'') for each of the
therapies. The first volumetric data set, the at least one two
dimensional image and the first arterial pressure drop need not to
be received more than once, since these form the same base data for
all the calculations for each of the pre-selected therapies. The
geometry modification and second pressure drop estimation (and,
optionally, the second fractional flow calculation) are performed
according to each of the selected arterial stenosis therapies. The
first arterial pressure drop and the second arterial pressure drop
(and, optionally, the second fractional flow reserve) for each of
the selected arterial stenosis therapies are displayed (in step
803) or used for further processing. In step 804 the physician
selects the arterial stenosis therapy based on the results he is
provided with. He may either select one of the pre-selected
therapies or decide to select another therapy, for which he still
may perform the method of the embodiment of FIG. 5.
While the invention has been illustrated and described in detail in
the drawings and foregoing description, such illustration and
description are to be considered illustrative or exemplary and not
restrictive; the invention is not limited to the disclosed
embodiments.
Other variations to the disclosed embodiments can be understood and
effected by those skilled in the art in practicing the claimed
invention, from a study of the drawings, the disclosure, and the
appended claims. In the claims, the word "comprising" does not
exclude other elements or steps, and the indefinite article "a" or
"an" does not exclude a plurality. A single processor or other unit
may fulfill the functions of several items recited in the claims.
The mere fact that certain measures are recited in mutually
different dependent claims does not indicate that a combination of
these measured cannot be used to advantage. A computer program may
be stored/distributed on a suitable medium, such as an optical
storage medium or a solid-state medium supplied together with or as
part of other hardware, but may also be distributed in other forms,
such as via the Internet or other wired or wireless
telecommunication systems. Any reference signs in the claims should
not be construed as limiting the scope.
* * * * *
References